The Past and Future of Tornado Prediction

Predicting tornadoes has come a long way since the first one was issued 65 years ago. Today, forecasters are trying to find ways to gather even more atmospheric data to give those in harm's way as much warning as possible.

The country's first official tornado watch was issued 65 years ago, on March 25, 1948. It was for Tinker Air Force Base, located just 12 miles northeast of Moore, Okla., where Monday's mile-wide tornado tore through town, killing at least 24 people and leveling entire neighborhoods along its 20-mile path. That warning, issued by Air Force meteorologists Capt. Robert Miller and Maj. Ernest Fawbush, was based on similar weather patterns from five days earlier, when a tornado ripped through the base. They got it right: The base hangered its planes before another tornado hit it that day.

"We've come a long way since the Tinker Air Force Base warnings, both in our understanding of tornadoes and weather patterns, and also in our technological ability," says Roger Edwards, a meteorologist who has spent the past 20 years at the National Weather Service's Storm Prediction Center in Norman, Okla. "For the most part tornado warning times in the 1950s and '60s was a matter of seconds."

Today, the average warning time is more like 15 minutes, and the weather service uses a combination of weather balloons—launched every 12 hours—satellite, radar, and weather-station feeds to make those predictions. Today forecasters look at long-range temperature data and wind-flow patterns that can produce atmospheric instability (warm air at the surface, cold air higher up), moisture, and wind shear (change of wind speed at different levels of elevation). Those latter ingredients are the building blocks of tornadoes.

Predicting Moore

While most of the news stories in the wake of Monday's tornadoes have reported the fact that there was a warning issued 16 minutes before the tornado touched down near Moore, the Storm Prediction Center was hard at work, warning local forecasters, the media, and local citizens long before that.

The Storm Prediction Center actually issued a moderate-outlook warning two days before the Moore tornado, another the day before the tornado hit, and another at 7 am Central time on May 20—the day the tornado hit.

The 7 am report warned: "STORMS THAT FORM FROM CENTRAL OK NORTHEASTWARD INTO SOUTHEAST KS AND MO APPEAR LIKELY TO ORGANIZE INTO BROKEN LINES AND CLUSTERS BY EARLY EVENING CAPABLE OF WIDESPREAD DAMAGING WINDS . . .LARGE HAIL . . . AND A FEW TORNADOES."

At 1:10 pm, the Storm Prediction Center issued a storm watch, alerting residents of most of Oklahoma, including Moore, that the conditions for a tornado were in effect and to prepare to take cover if one developed. By 2:08, the National Weather Service office in Norman, which handles tornado warnings for the area, and which is next door to the Strom Prediction Center, began issuing increasingly dire alerts. They also took to their Twitter feed @NWSNorman, writing:

2:08 p.m.: "Storms developing near Blanchard and Tuttle, moving NE at 30mph. Stay alert Norman, Moore, and S OKC. Not severe yet." 2:30 p.m.: "People in south OKC, Moore and north Norman need to pay VERY close attention to the storm near Newcastle." 2:34 p.m.: "One warning forecaster focusing on big supercell west of OKC." 2:39 p.m.: "Storm west of Newcastle is intensifying and showing some rotation. Stay alert! No tornado warning yet."

At 2:40 pm, 16 minutes before the tornado touched down in Newcastle, and 36 minutes before hitting Moore, a tornado warning was issued across all media outlets and weather radios, and again on Twitter, where the NWS wrote: "TORNADO WARNING for OKC metro! Developing tornado near Newcastle moving E 20 mph. Take shelter!!"

Oklahoma City's local news teams, famous for their severe weather coverage, were on the air. In Moore, the city's network tornado sirens began wailing. A city emergency-alert system that dials city phone numbers and plays a warning was activated. At 2:56 pm, the tornado tore across Moore.

Storm Prediction in the Future

Officially, tornado watches are issued by the Storm Prediction Center. They are, in effect, an alert that the weather conditions will likely exist for a tornado to form later in the day. Watches typically cover 3- to 8-hour periods and cover areas as large as 25,000 square miles—about half the size of Mississippi. Warnings, on the other hand, come from the National Weather Service offices and are issued when a tornado is imminent—typically about 15 minutes before touchdown.

"We're trying to bridge the gap between watches and warnings so we can issue specific notices hours in advance that a tornado will touch down in a specific county, but we're several years off," Edwards says. "It all comes down to the data and modeling the data, and that takes a lot of computing power. Once you get above the surface, our data is not as dense as it could be. We'll need to launch more weather balloons and get more frequent sampling from satellites."

Another step in improving tornado forecasts nationwide is the linking of various weather reporting stations into a network of networks with an endless stream of data. Oklahoma has already developed such a network, but the goal is to expand this nationally.

Until that time, people's best strategy for staying out of harm's way is to treat tornado watches incredibly seriously. These watches are, in effect, an early warning system that should put you on notice that you're in danger. By the time an actual warning is issued you're most likely looking at just minutes to react, not hours.

"That 16-minute warning doesn't sound like much," Edwards says. "But it's a tremendous improvement compared to warning times in the past. The tornado path was 20 miles long and lasted for 40 minutes. Hundreds of lives were saved because the warnings for those spots further down the tornado track were even greater than that 16 minutes."

John Galvin covers natural and man-made disasters for Popular Mechanics. Follow him on Twitter at @JohnPGalvin.

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